This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency o...This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency of timer output waveform which is measured using a digital storage oscillator(DSO)is almost linearly proportional to the applied input voltage.Hence we obtain a linear relationship between the frequency of timer output waveform and the input voltage.Because of its quasi-digital output,the main advantages of this developed converter are linear input-output relationship,small size,easy portabilityand high cost performance.In addition,the timer output waveform can be directly interfaced with personal computer or microprocessor/microcontroller for further processing of the input voltage signal without intervening any analog-to-digital converter(ADC).展开更多
In this paper, a linear-to-circular polarization converter using a three-layer frequency selective surface based on Ishaped circular structure resonant is presented and investigated. Numerical simulations exhibit that...In this paper, a linear-to-circular polarization converter using a three-layer frequency selective surface based on Ishaped circular structure resonant is presented and investigated. Numerical simulations exhibit that when the normal ypolarized waves impinge on this device propagating towards ＋z direction, the two orthogonal components of the transmitted waves have a 90° phase difference as well as the nearly equal amplitudes at the resonant frequency of 7.04 GHz, which means that the left-hand circular polarization is realized in transmission. For validating the proposed design, a prototype which consists of 25 × 25 elements has been designed, manufactured and measured. The measured results are in good agreement with the simulated ones, showing that the polarization conversion transmission is over-3 dB in the frequency range of 5.22–8.08 GHz and the axial ratio is below 3 dB from 5.86 GHz to 7.34 GHz.展开更多
Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode（CCM） are studied in this paper. First of all, the two-dimensional discrete mapping model is established....Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode（CCM） are studied in this paper. First of all, the two-dimensional discrete mapping model is established. Next, reference current at the period-doubling point and the border of inductor current are derived. Then, the bifurcation diagrams are drawn with the aid of MATLAB. Meanwhile, circuit simulations are executed with PSIM, and time domain waveforms as well as phase portraits in i_L–v_C plane are plotted with MATLAB on the basis of simulation data. After that, we construct the Jacobian matrix and analyze the stability of the system based on the roots of characteristic equations. Finally, the validity of theoretical analysis has been verified by circuit testing. The simulation and experimental results show that,with the increase of reference current I_（ref）, the corresponding switching frequency f is approaching to low-frequency stage continuously when the period-doubling bifurcation happens, leading to the converter tending to be unstable. With the increase of f, the corresponding Irefdecreases when the period-doubling bifurcation occurs, indicating the stable working range of the system becomes smaller.展开更多
Petroleum is an important energy source and occupies a very critical position in my country's economic development. In recent years, my country's crude oil production and sales have increased significantly. Ho...Petroleum is an important energy source and occupies a very critical position in my country's economic development. In recent years, my country's crude oil production and sales have increased significantly. However, due to factors such as rising international oil prices and weak domestic demand, the development of the oil industry has experienced a bottleneck period and serious overcapacity. Therefore, for the current production of petrochemical enterprises However, with the rapid growth of the national economy, the increase in energy demand and the increase in environmental protection requirements, higher standards have been put forward for power supply. Problems are analyzed and corresponding solutions are formulated to promote the healthy and orderly operation of the entire industrial system.展开更多
In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator a...In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator and universal frequency to digital converter (UFDC). Due to variation in angular displacement in the variable area type capacitor which is connected in the timer based astable circuit,capacitance changes which in turn changes the time period of the timer circuit output. The time period of the timer output waveform is linear with the capacitance and hence linear with angular displacement. The timer output is further processed with UFDC for the measurement. The experimental results show that the time period is linear with the angular displacement in the range of 0- 180° and the uncertainty we should associate it with this average time period value is the standard deviation of the mean,often called the standard error (SE),which is ± 0.023 μs. Because of the simplicity,this measurement system can be used in both electronic and industrial instrumentation.展开更多
Because the leakage protection circuit in traction motor of coal mining machine is impacted by frequency converter devices,malfunctions appear frequently.This paper makes an in-depth analysis,proposes a solution of us...Because the leakage protection circuit in traction motor of coal mining machine is impacted by frequency converter devices,malfunctions appear frequently.This paper makes an in-depth analysis,proposes a solution of using the subtraction circuit to offset interference signals and conducts a simulation analysis.The above scheme,which is simple and easily realized,can improve the reliability of leakage protection device in traction motor.展开更多
All solid state UV lasers have been in demand for various industrial and medical applications because of the convenient operation procedure and cost effectiveness as alternative to corrosive gas based excimer laser.Th...All solid state UV lasers have been in demand for various industrial and medical applications because of the convenient operation procedure and cost effectiveness as alternative to corrosive gas based excimer laser.The performance of such lasers seems to depend on the capability and reliability of UV frequency converter.In the third decade,CsLiB 6O 10 (CLBO)and Gd xY 1 x Ca 4O(BO 3) 3 (GdYCOB)were developed by the authors group.CLBO is the most effective nonlinear optical crystal to generate high power fourth and fifth harmonics of Nd∶YAG laser.GdYCOB is the first material which can achieve noncritical phase matching (NCPM) condition for THG of Nd∶YAG laser.The NCPM condition is advantageous owing to its large angular acceptance and the elimination of walk off between fundamental and harmonic lights.On the other hand,reliability is very importmat for actual application of these crystals.Here,we will present about techniques to improve durability of NLO crystals for high power UV light generation.For instance,we found that removal of surface polishing compound by means of ion beam etching can imrpove surface durability of CLBO.Also,we will discussed about photo induced damages in GdYCOB and its solution.展开更多
The control system takes the outlet pressure of the chiller as the main control object, adopts the sensor technology to collect and monitor the outlet air bag pressure in real time, and automatically completes the pur...The control system takes the outlet pressure of the chiller as the main control object, adopts the sensor technology to collect and monitor the outlet air bag pressure in real time, and automatically completes the purging PID control according to the set value.展开更多
Gas pressurized fan speed control and remote monitoring was achieved based on three sets of gas pressure MM440 frequency converter control system, through the Profibus-DP network transmission of exchange data and sign...Gas pressurized fan speed control and remote monitoring was achieved based on three sets of gas pressure MM440 frequency converter control system, through the Profibus-DP network transmission of exchange data and signal instructions. In operation, one converter which adopted ＂ power-off reset＂ has broken down, so as to cause two other gas pressurized frequency converter tripping. This paper proposed method to achieve capture and process failures, and application to converter control system. The result shows that the present method solves the fault, improves the system operation stability and meets the requirement of production.展开更多
The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high pro...The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high production cost. Chinas automation industry has experienced rapid development for many years, and the inverter has made great progress in product performance and appearance. The self-developed electric shovel electric control system can provide a complete set of solutions for 10m3 ~ 55m3 electric shovel AC telex system and related products, and completed the localization and digital transformation of electric shovels.展开更多
Nowadays, the coal mine is more and more demanding for electrical equipment, and the use of high voltage frequency converter in the motor control system has become more and more widespread. The working conditions of c...Nowadays, the coal mine is more and more demanding for electrical equipment, and the use of high voltage frequency converter in the motor control system has become more and more widespread. The working conditions of coal mine have high requirements for the reliability of high voltage frequency conversion equipment, which requires that the equipment can quickly resume operation after failure. However, the fault of frequency converter itself is often difficult to eliminate, resulting in a long troubleshooting time, which has a certain impact on the continuous production of coal mine. At the same time, the application effect of high voltage frequency converter on electric shovel is studied.展开更多
In this paper, a new predictive control strategy for current source matrix converter (CSMC) is presented. Proposed predictive control strategy allows for creating output voltages with boost type voltage transfer ratio...In this paper, a new predictive control strategy for current source matrix converter (CSMC) is presented. Proposed predictive control strategy allows for creating output voltages with boost type voltage transfer ratio and desired frequency. The description of predictive control circuit of the CSMC is presented. Furthermore the simulation test results to confirm functionality of the proposed control strategy and converter properties under this strategy are shown.展开更多
A multicellular DCX （dc-dc transformer） using unregulated cell converters has been proposed for the environmentally friendly data centers. The high speed cell converter with the switching frequency over MHz behaves ...A multicellular DCX （dc-dc transformer） using unregulated cell converters has been proposed for the environmentally friendly data centers. The high speed cell converter with the switching frequency over MHz behaves as an ideal transformer, and this behavior solves the voltage imbalance issue in the multicellular converter topology. The analysis of the unregulated cell converter is conducted by using the state space averaging method, and the operation condition for the ideal transformer is specified. The behavior of the multicellular DCX using the high speed cell converters has been also analyzed, and the voltage imbalance issue among cell converters is discussed quantitatively. A prototype of a 19.2 kW 384 V-384 V multicellular DCX using sixty-four unregulated cell converters is fabricated and the validity of the analyses is verified.展开更多
This Letter demonstrates the application of dual-output modulation in a photonic analog-to-digital converter （PADC） with a high sampling rate and resolution. The PADC is time-wavelength interleaved and based on an a...This Letter demonstrates the application of dual-output modulation in a photonic analog-to-digital converter （PADC） with a high sampling rate and resolution. The PADC is time-wavelength interleaved and based on an actively mode-locked laser. According to theoretical analysis, the dual-output PADC system shows a better linearity for achieving a higher dynamic range. In the experiment, third-order distortion is significantly sup- pressed by -40 dB when the dual-output modulator is used and the effective number of bits of the PADC has reached 9.0 bits below 0.2 GHz and 6.4 bits at 6.1 GHz in our PADC with a sampling rate of 20 GS/s.展开更多
Synchronous condensers(SCs)are generally used at the receiving-end stations of ultra-high-voltage direct current(UHVDC)transmission systems due to their strong reactive power support and flexible regulation of reactiv...Synchronous condensers(SCs)are generally used at the receiving-end stations of ultra-high-voltage direct current(UHVDC)transmission systems due to their strong reactive power support and flexible regulation of reactive power according to the interconnected grids operating conditions.In this paper,different starting control schemes of a SC integrated power grid are investigated providing four main contributions:1)The principle of reactive power support of the SC on the interconnected power grid is analytically studied,providing the establishment of mathematical models.2)Four different starting control schemes are developed for the initialization and SC integration,i.e.in Scheme 1,a preset initial falling speed is directly utilized without initialization;in Scheme 2,a black start sequential control approach with a static frequency converter(SFC)is proposed;in Scheme 3,PI/PD/PID controllers are respectively applied for the excitation device at the speed-falling stage;in Scheme 4,a pre-insertion approach of an energy absorption component with R/L/RL is utilized to suppress the surges at the SC integration instant.3)The dynamic behaviors of four different starting schemes at specific operating stages are evaluated.4)The success rate of SC integration is analyzed to evaluate starting control performance.Performance of the SC interconnected system with four different starting control schemes is evaluated in the timedomain simulation environment PSCAD/EMTDC^(TM).The results prove the superiority of the proposed starting control approach in Scheme 4.展开更多
A 10 MHz ripple-based on-time controlled buck converter is presented. A novel low-cost dual ripple compensation, which consists of coupling capacitor compensation and passive equivalent series resistance compensation,...A 10 MHz ripple-based on-time controlled buck converter is presented. A novel low-cost dual ripple compensation, which consists of coupling capacitor compensation and passive equivalent series resistance compensation, is proposed to achieve a fast load transient response and robust stability simultaneously. Implemented in a 2P4M 0.35 um CMOS process, the converter achieves fix-frequency output with a ripple of below 10 mV and an overshoot of 10 mV at 400 mA step load transient response. With width optimization of the power transistors in an ultra-heavy load and PFM control in a light load, the efficiency stays at over 83% for a load range from 20 mA to 1.5 A and the peak efficiency reaches 90.16%.展开更多
文摘This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency of timer output waveform which is measured using a digital storage oscillator(DSO)is almost linearly proportional to the applied input voltage.Hence we obtain a linear relationship between the frequency of timer output waveform and the input voltage.Because of its quasi-digital output,the main advantages of this developed converter are linear input-output relationship,small size,easy portabilityand high cost performance.In addition,the timer output waveform can be directly interfaced with personal computer or microprocessor/microcontroller for further processing of the input voltage signal without intervening any analog-to-digital converter(ADC).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61471387,61271250,and 61571460)
文摘In this paper, a linear-to-circular polarization converter using a three-layer frequency selective surface based on Ishaped circular structure resonant is presented and investigated. Numerical simulations exhibit that when the normal ypolarized waves impinge on this device propagating towards ＋z direction, the two orthogonal components of the transmitted waves have a 90° phase difference as well as the nearly equal amplitudes at the resonant frequency of 7.04 GHz, which means that the left-hand circular polarization is realized in transmission. For validating the proposed design, a prototype which consists of 25 × 25 elements has been designed, manufactured and measured. The measured results are in good agreement with the simulated ones, showing that the polarization conversion transmission is over-3 dB in the frequency range of 5.22–8.08 GHz and the axial ratio is below 3 dB from 5.86 GHz to 7.34 GHz.
基金Project supported by the National Natural Science Foundation of China(Grant No.61376029)the Fundamental Research Funds for the Central Universities,Chinathe College Graduate Research and Innovation Program of Jiangsu Province,China(Grant No.SJLX15 0092)
文摘Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode（CCM） are studied in this paper. First of all, the two-dimensional discrete mapping model is established. Next, reference current at the period-doubling point and the border of inductor current are derived. Then, the bifurcation diagrams are drawn with the aid of MATLAB. Meanwhile, circuit simulations are executed with PSIM, and time domain waveforms as well as phase portraits in i_L–v_C plane are plotted with MATLAB on the basis of simulation data. After that, we construct the Jacobian matrix and analyze the stability of the system based on the roots of characteristic equations. Finally, the validity of theoretical analysis has been verified by circuit testing. The simulation and experimental results show that,with the increase of reference current I_（ref）, the corresponding switching frequency f is approaching to low-frequency stage continuously when the period-doubling bifurcation happens, leading to the converter tending to be unstable. With the increase of f, the corresponding Irefdecreases when the period-doubling bifurcation occurs, indicating the stable working range of the system becomes smaller.
文摘Petroleum is an important energy source and occupies a very critical position in my country's economic development. In recent years, my country's crude oil production and sales have increased significantly. However, due to factors such as rising international oil prices and weak domestic demand, the development of the oil industry has experienced a bottleneck period and serious overcapacity. Therefore, for the current production of petrochemical enterprises However, with the rapid growth of the national economy, the increase in energy demand and the increase in environmental protection requirements, higher standards have been put forward for power supply. Problems are analyzed and corresponding solutions are formulated to promote the healthy and orderly operation of the entire industrial system.
文摘In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator and universal frequency to digital converter (UFDC). Due to variation in angular displacement in the variable area type capacitor which is connected in the timer based astable circuit,capacitance changes which in turn changes the time period of the timer circuit output. The time period of the timer output waveform is linear with the capacitance and hence linear with angular displacement. The timer output is further processed with UFDC for the measurement. The experimental results show that the time period is linear with the angular displacement in the range of 0- 180° and the uncertainty we should associate it with this average time period value is the standard deviation of the mean,often called the standard error (SE),which is ± 0.023 μs. Because of the simplicity,this measurement system can be used in both electronic and industrial instrumentation.
文摘Because the leakage protection circuit in traction motor of coal mining machine is impacted by frequency converter devices,malfunctions appear frequently.This paper makes an in-depth analysis,proposes a solution of using the subtraction circuit to offset interference signals and conducts a simulation analysis.The above scheme,which is simple and easily realized,can improve the reliability of leakage protection device in traction motor.
文摘All solid state UV lasers have been in demand for various industrial and medical applications because of the convenient operation procedure and cost effectiveness as alternative to corrosive gas based excimer laser.The performance of such lasers seems to depend on the capability and reliability of UV frequency converter.In the third decade,CsLiB 6O 10 (CLBO)and Gd xY 1 x Ca 4O(BO 3) 3 (GdYCOB)were developed by the authors group.CLBO is the most effective nonlinear optical crystal to generate high power fourth and fifth harmonics of Nd∶YAG laser.GdYCOB is the first material which can achieve noncritical phase matching (NCPM) condition for THG of Nd∶YAG laser.The NCPM condition is advantageous owing to its large angular acceptance and the elimination of walk off between fundamental and harmonic lights.On the other hand,reliability is very importmat for actual application of these crystals.Here,we will present about techniques to improve durability of NLO crystals for high power UV light generation.For instance,we found that removal of surface polishing compound by means of ion beam etching can imrpove surface durability of CLBO.Also,we will discussed about photo induced damages in GdYCOB and its solution.
文摘The control system takes the outlet pressure of the chiller as the main control object, adopts the sensor technology to collect and monitor the outlet air bag pressure in real time, and automatically completes the purging PID control according to the set value.
文摘Gas pressurized fan speed control and remote monitoring was achieved based on three sets of gas pressure MM440 frequency converter control system, through the Profibus-DP network transmission of exchange data and signal instructions. In operation, one converter which adopted ＂ power-off reset＂ has broken down, so as to cause two other gas pressurized frequency converter tripping. This paper proposed method to achieve capture and process failures, and application to converter control system. The result shows that the present method solves the fault, improves the system operation stability and meets the requirement of production.
文摘The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high production cost. Chinas automation industry has experienced rapid development for many years, and the inverter has made great progress in product performance and appearance. The self-developed electric shovel electric control system can provide a complete set of solutions for 10m3 ~ 55m3 electric shovel AC telex system and related products, and completed the localization and digital transformation of electric shovels.
文摘Nowadays, the coal mine is more and more demanding for electrical equipment, and the use of high voltage frequency converter in the motor control system has become more and more widespread. The working conditions of coal mine have high requirements for the reliability of high voltage frequency conversion equipment, which requires that the equipment can quickly resume operation after failure. However, the fault of frequency converter itself is often difficult to eliminate, resulting in a long troubleshooting time, which has a certain impact on the continuous production of coal mine. At the same time, the application effect of high voltage frequency converter on electric shovel is studied.
文摘In this paper, a new predictive control strategy for current source matrix converter (CSMC) is presented. Proposed predictive control strategy allows for creating output voltages with boost type voltage transfer ratio and desired frequency. The description of predictive control circuit of the CSMC is presented. Furthermore the simulation test results to confirm functionality of the proposed control strategy and converter properties under this strategy are shown.
文摘A multicellular DCX （dc-dc transformer） using unregulated cell converters has been proposed for the environmentally friendly data centers. The high speed cell converter with the switching frequency over MHz behaves as an ideal transformer, and this behavior solves the voltage imbalance issue in the multicellular converter topology. The analysis of the unregulated cell converter is conducted by using the state space averaging method, and the operation condition for the ideal transformer is specified. The behavior of the multicellular DCX using the high speed cell converters has been also analyzed, and the voltage imbalance issue among cell converters is discussed quantitatively. A prototype of a 19.2 kW 384 V-384 V multicellular DCX using sixty-four unregulated cell converters is fabricated and the validity of the analyses is verified.
基金supported by the National Natural Science Foundation of China(Nos.61535006 and 61571292)the Specialized Research Fund within the Doctoral Program through the Ministry of Education(No.20130073130005)the State Key Laboratory Project of Shanghai Jiao Tong University(No.2014ZZ03016)
文摘This Letter demonstrates the application of dual-output modulation in a photonic analog-to-digital converter （PADC） with a high sampling rate and resolution. The PADC is time-wavelength interleaved and based on an actively mode-locked laser. According to theoretical analysis, the dual-output PADC system shows a better linearity for achieving a higher dynamic range. In the experiment, third-order distortion is significantly sup- pressed by -40 dB when the dual-output modulator is used and the effective number of bits of the PADC has reached 9.0 bits below 0.2 GHz and 6.4 bits at 6.1 GHz in our PADC with a sampling rate of 20 GS/s.
基金supported by the National Natural Science Foundation of China under Grant 51807091the Natural Science Foundation of Jiangsu Province BK20180478+2 种基金the China Postdoctoral Science Foundation under Grant 2019M661846the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources under Grant LAPS20016Engineering and Physical Sciences Research Council under Grant EP/N032888/1.
文摘Synchronous condensers(SCs)are generally used at the receiving-end stations of ultra-high-voltage direct current(UHVDC)transmission systems due to their strong reactive power support and flexible regulation of reactive power according to the interconnected grids operating conditions.In this paper,different starting control schemes of a SC integrated power grid are investigated providing four main contributions:1)The principle of reactive power support of the SC on the interconnected power grid is analytically studied,providing the establishment of mathematical models.2)Four different starting control schemes are developed for the initialization and SC integration,i.e.in Scheme 1,a preset initial falling speed is directly utilized without initialization;in Scheme 2,a black start sequential control approach with a static frequency converter(SFC)is proposed;in Scheme 3,PI/PD/PID controllers are respectively applied for the excitation device at the speed-falling stage;in Scheme 4,a pre-insertion approach of an energy absorption component with R/L/RL is utilized to suppress the surges at the SC integration instant.3)The dynamic behaviors of four different starting schemes at specific operating stages are evaluated.4)The success rate of SC integration is analyzed to evaluate starting control performance.Performance of the SC interconnected system with four different starting control schemes is evaluated in the timedomain simulation environment PSCAD/EMTDC^(TM).The results prove the superiority of the proposed starting control approach in Scheme 4.
文摘A 10 MHz ripple-based on-time controlled buck converter is presented. A novel low-cost dual ripple compensation, which consists of coupling capacitor compensation and passive equivalent series resistance compensation, is proposed to achieve a fast load transient response and robust stability simultaneously. Implemented in a 2P4M 0.35 um CMOS process, the converter achieves fix-frequency output with a ripple of below 10 mV and an overshoot of 10 mV at 400 mA step load transient response. With width optimization of the power transistors in an ultra-heavy load and PFM control in a light load, the efficiency stays at over 83% for a load range from 20 mA to 1.5 A and the peak efficiency reaches 90.16%.
